The invention relates to an illumination device for a motor vehicle including a light source constructed of a number of semiconductor diodes and including an optical device arranged in a housing for generating a pre-defined light distribution from the light of the light source.
Today, in the field of motor vehicle engineering, there is increasing usage of illumination devices based on semiconductor diodes, especially in the form of LEDs. Normally the light source made of semiconductor diodes is combined with an optical device that generates the light distribution of the illumination device to form one unit that is built into the housing of the illumination device. It has proved to be a drawback that by integrating the light source and the optical device in one unit, the exchange of a defective light source is complicated because, for this to happen, the entire unit must be removed from the housing of the illumination device.
The object of the invention is to create a novel illumination device for a motor vehicle, the components of which are more easily accessible, at least in part.
This and other objects are achieved according to the invention by providing an illumination device for a motor vehicle including a light source constructed of a number of semiconductor diodes and including an optical device arranged in a housing for generating a pre-defined light distribution from the light of the light source. The light source is rigidly connected to the housing. At least one optical waveguide is provided that guides the light of the light source to the optical device.
The inventive illumination device is provided for a motor vehicle, in particular a privately operated vehicle, and possibly also a truck. It includes a light source made from a number of semiconductor diodes and includes an optical device arranged in a housing for generating a pre-defined light distribution from the light of the light source. The structure of such an optical device is known per se and may be different depending on the application. In particular, the optical device may include one or a plurality of reflectors (e.g. half-shell reflectors) and/or one or a plurality of lenses for generating the appropriate light distribution.
The inventive illumination device is distinguished in that the light source is rigidly connected to the housing and, furthermore, at least one optical waveguide is provided for guiding the light of the light source to the optical device. The light source is thus preferably a separate unit that is separated from the optical device. It is easier to disassemble and exchange the light source due to the rigid connection of the light source to the housing. The optical waveguide ensures that the light of the light source travels to the optical device.
The light source preferably includes a plurality of semiconductor diodes, and especially 3 to 8 semiconductor diodes. It is also possible, however, for the light source to include only one diode. In one preferred embodiment, the light source includes as semiconductor diode(s) one or more laser diodes and preferably exclusively just laser diodes. Laser diodes are distinguished by a very high light brightness and small structural dimensions. Preferably, laser diodes that each have a power of at least 1 W and, in particular, between 1.5 and 5 W, are used in the inventive illumination device.
In one particularly preferred embodiment, the at least one optical waveguide is a flexible optical fiber cable. Particularly simple assembly and disassembly of the light source and the optical device is assured due to the flexibility of the optical fiber cable. In particular, when using a flexible optical fiber cable, there is no need for a complex mechanical design to ensure the incidence of the light from the light source into the optical device.
In another preferred embodiment of the invention, monochromatic light is produced with the light source, wherein a conversion element for converting the monochromatic light to white light is provided. Such conversion elements are known per se. For instance, with blue laser diodes having an emission wavelength of 450 nm/405 nm, a phosphorous conversion element made of nitride phosphor, oxide nitride phosphor or cerium-doped YAG phosphor may be used for generating white light.
The conversion element, which is embodied in particular as a layer, may be arranged at different positions depending on the design of the invention. In particular, the conversion element may be positioned at an end of the at least one optical waveguide and disposed adjacent to the light source or even at an end of the at least one optical waveguide and disposed remote from the light source.
In another preferred embodiment of the inventive illumination device, a sensor for detecting the light intensity in the optical waveguide is provided at one end of the at least one optical waveguide, disposed remote from the light source. This creates the opportunity to detect defects of the light source or the transmission segment to the optical device in a simple manner via a single sensor, and thus to detect malfunctions. In particular, a malfunction is established when the detected light intensity is below a predetermined threshold value that permits it to be concluded that there is a defect in the light source or in the optical waveguide.
In another preferred embodiment of the invention, the light source is attached (directly) to the housing. Because of this, the light source is particularly easy to access and is easy to disassemble. The attachment of the light source to the housing is preferably designed such that the light source may be removed from outside of the housing. In particular, at least part of the light source is not enclosed by the housing, so that the accessibility of the light source is further improved.
In one preferred variant of the inventive illumination device, a heat sink is provided at the light source for cooling the light source, wherein the heat sink is preferably thermally coupled to cooler parts of the motor vehicle. The term heat sink shall be understood in a very broad context and may include both active and passive cooling devices or a combination of such cooling devices. At least part of the heat sink is preferably arranged outside of the housing so that the heat sink may be cooled using external air. In one particularly preferred variant, the heat sink includes a passive cooling body that preferably includes surface area-enlarging elements, such as, e.g., ribs, fins and/or pins, for effective cooling.
For improving cooling capacity, in another embodiment of the invention, a fan is provided at the heat sink for producing an air flow. In another variant, the heat sink is connected to an air guide for supplying cooling air to the heat sink. This variant may be combined in particular with a heat sink that has a fan so that the air guide acts as an intake guide through which the fan draws in air from a cooler area in the motor vehicle.
In another embodiment of the inventive illumination device, the optical device is movable, and in particular is pivotable and/or rotatable, inside the housing. The movement of the optical device may be effected, e.g., using an electric motor that is preferably controlled via a control device of the motor vehicle. In this manner it is possible to realize functionalities such as an adaptive light, a cornering lamp, and the like.
In another embodiment of the invention, the optical device is a self-contained unit or a module that may be removed as a whole from the illumination device. Thus permits the optical device to be exchanged in a simple manner when there are defects.
The inventive illumination device may assume different functionalities depending on the application. In one embodiment, the illumination device forms a headlight. A headlight is distinguished in that it actively illuminates the surroundings of the vehicle. In some cases it is possible for the inventive illumination device also to form an indicator or signal light that is distinguished in that it merely provides a signal for other motorists. In one preferred variant, the illumination device is embodied such that during operation a low beam characteristic is generated as a pre-defined light distribution. It is also possible for the illumination device to be embodied such that during operation it generates a high beam characteristic as the pre-defined light distribution.
In addition to the inventive illumination device, the invention furthermore relates to a motor vehicle that includes one or more of the inventive illumination devices.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.